HELP - Bread did not rise

Good morning

I bake about 50 loaves for the local morning market. Last night my loaves just did not want to rise. It is freezing here in South Africa and I was wondering if the cold could have killed the yeast. I autolyzed my flour with lukewarm water, but by the time I added the rest of the ingredients, the water was icecold already. I have always done it this way, but was wondering if the very cold weather could've been the cause. We don't have any heaters going except the fireplace. I do have a prover, but while the large amounts of dough is in the bowls busy autolyzing, it doesn't fit in the prover. I am going to test the yeast today, since it was a new packet that I opened yesterday.